/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.analysis.standard;

import java.io.IOException;
import java.io.Reader;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.Version;

/** A grammar-based tokenizer constructed with JFlex
 *
 * <p> This should be a good tokenizer for most European-language documents:
 *
 * <ul>
 *   <li>Splits words at punctuation characters, removing punctuation. However, a 
 *     dot that's not followed by whitespace is considered part of a token.
 *   <li>Splits words at hyphens, unless there's a number in the token, in which case
 *     the whole token is interpreted as a product number and is not split.
 *   <li>Recognizes email addresses and internet hostnames as one token.
 * </ul>
 *
 * <p>Many applications have specific tokenizer needs.  If this tokenizer does
 * not suit your application, please consider copying this source code
 * directory to your project and maintaining your own grammar-based tokenizer.
 *
 * <a name="version"/>
 * <p>You must specify the required {@link Version}
 * compatibility when creating ClassicAnalyzer:
 * <ul>
 *   <li> As of 2.4, Tokens incorrectly identified as acronyms
 *        are corrected (see <a href="https://issues.apache.org/jira/browse/LUCENE-1068">LUCENE-1608</a>
 * </ul>
 * 
 * ClassicTokenizer was named StandardTokenizer in Lucene versions prior to 3.1.
 * As of 3.1, {@link StandardTokenizer} implements Unicode text segmentation,
 * as specified by UAX#29.
 */

public final class ClassicTokenizer extends Tokenizer {
    /** A private instance of the JFlex-constructed scanner */
    private StandardTokenizerInterface scanner;

    public static final int ALPHANUM = 0;
    public static final int APOSTROPHE = 1;
    public static final int ACRONYM = 2;
    public static final int COMPANY = 3;
    public static final int EMAIL = 4;
    public static final int HOST = 5;
    public static final int NUM = 6;
    public static final int CJ = 7;

    /**
     * @deprecated this solves a bug where HOSTs that end with '.' are identified
     *             as ACRONYMs.
     */
    @Deprecated
    public static final int ACRONYM_DEP = 8;

    /** String token types that correspond to token type int constants */
    public static final String[] TOKEN_TYPES = new String[] { "<ALPHANUM>", "<APOSTROPHE>", "<ACRONYM>", "<COMPANY>", "<EMAIL>", "<HOST>", "<NUM>", "<CJ>", "<ACRONYM_DEP>" };

    private boolean replaceInvalidAcronym;

    private int maxTokenLength = StandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH;

    /** Set the max allowed token length.  Any token longer
     *  than this is skipped. */
    public void setMaxTokenLength(int length) {
        this.maxTokenLength = length;
    }

    /** @see #setMaxTokenLength */
    public int getMaxTokenLength() {
        return maxTokenLength;
    }

    /**
     * Creates a new instance of the {@link ClassicTokenizer}.  Attaches
     * the <code>input</code> to the newly created JFlex scanner.
     *
     * @param input The input reader
     *
     * See http://issues.apache.org/jira/browse/LUCENE-1068
     */
    public ClassicTokenizer(Version matchVersion, Reader input) {
        super();
        init(input, matchVersion);
    }

    /**
     * Creates a new ClassicTokenizer with a given {@link AttributeSource}. 
     */
    public ClassicTokenizer(Version matchVersion, AttributeSource source, Reader input) {
        super(source);
        init(input, matchVersion);
    }

    /**
     * Creates a new ClassicTokenizer with a given {@link org.apache.lucene.util.AttributeSource.AttributeFactory} 
     */
    public ClassicTokenizer(Version matchVersion, AttributeFactory factory, Reader input) {
        super(factory);
        init(input, matchVersion);
    }

    private final void init(Reader input, Version matchVersion) {
        this.scanner = new ClassicTokenizerImpl(input);

        if (matchVersion.onOrAfter(Version.LUCENE_24)) {
            replaceInvalidAcronym = true;
        } else {
            replaceInvalidAcronym = false;
        }
        this.input = input;
    }

    // this tokenizer generates three attributes:
    // term offset, positionIncrement and type
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
    private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class);
    private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);

    /*
     * (non-Javadoc)
     *
     * @see org.apache.lucene.analysis.TokenStream#next()
     */
    @Override
    public final boolean incrementToken() throws IOException {
        clearAttributes();
        int posIncr = 1;

        while (true) {
            int tokenType = scanner.getNextToken();

            if (tokenType == StandardTokenizerInterface.YYEOF) {
                return false;
            }

            if (scanner.yylength() <= maxTokenLength) {
                posIncrAtt.setPositionIncrement(posIncr);
                scanner.getText(termAtt);
                final int start = scanner.yychar();
                offsetAtt.setOffset(correctOffset(start), correctOffset(start + termAtt.length()));
                // This 'if' should be removed in the next release. For now, it converts
                // invalid acronyms to HOST. When removed, only the 'else' part should
                // remain.
                if (tokenType == ClassicTokenizer.ACRONYM_DEP) {
                    if (replaceInvalidAcronym) {
                        typeAtt.setType(ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.HOST]);
                        termAtt.setLength(termAtt.length() - 1); // remove extra '.'
                    } else {
                        typeAtt.setType(ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.ACRONYM]);
                    }
                } else {
                    typeAtt.setType(ClassicTokenizer.TOKEN_TYPES[tokenType]);
                }
                return true;
            } else
                // When we skip a too-long term, we still increment the
                // position increment
                posIncr++;
        }
    }

    @Override
    public final void end() {
        // set final offset
        int finalOffset = correctOffset(scanner.yychar() + scanner.yylength());
        offsetAtt.setOffset(finalOffset, finalOffset);
    }

    @Override
    public void reset(Reader reader) throws IOException {
        super.reset(reader);
        scanner.yyreset(reader);
    }

    /**
     * Prior to https://issues.apache.org/jira/browse/LUCENE-1068, ClassicTokenizer mischaracterized as acronyms tokens like www.abc.com
     * when they should have been labeled as hosts instead.
     * @return true if ClassicTokenizer now returns these tokens as Hosts, otherwise false
     *
     * @deprecated Remove in 3.X and make true the only valid value
     */
    @Deprecated
    public boolean isReplaceInvalidAcronym() {
        return replaceInvalidAcronym;
    }

    /**
     *
     * @param replaceInvalidAcronym Set to true to replace mischaracterized acronyms as HOST.
     * @deprecated Remove in 3.X and make true the only valid value
     *
     * See https://issues.apache.org/jira/browse/LUCENE-1068
     */
    @Deprecated
    public void setReplaceInvalidAcronym(boolean replaceInvalidAcronym) {
        this.replaceInvalidAcronym = replaceInvalidAcronym;
    }
}
